美国国家公共电台 NPR Biologist Jonathan Losos Explores 'Convergent Evolution' In 'Improbable Destinies'

 

ROBERT SIEGEL, HOST:

Biologist Jonathan Losos and I have at least one thing in common - we were both blown away by the late paleontologist Stephen Jay Gould's 1989 book "Wonderful Life." Gould saw evolution as being all about odd contingencies¹, accidents. Had one evolutionary² step gone a different way, life on Earth could've ended up radically³ different. Losos read the book, and Gould helped inspire him to become a biologist. He's a professor at Harvard and the author of a new book called "Improbable Destinies." One thing he is not anymore is quite so much a believer in Gould's insistence⁴ on chance and contingency⁵ driving evolutionary change. Jonathan Losos, welcome to the program.

JONATHAN LOSOS: Thank you very much; a pleasure to be here.

SIEGEL: At the heart of your book and your conversion⁶, I guess, is the growth in recent decades of an understanding of convergence as a principle in evolution. Can you define convergence for us?

LOSOS: Well, convergent⁸ evolution is when two species independently evolve to be similar.

SIEGEL: And the best example that you give that I can recall is the remains⁹ of an aquatic¹⁰ dinosaur¹¹, a dolphin and a shark. They all developed dorsal¹² fins¹³, flippers, sleek¹⁴ bodies, but they didn't all develop from the same set of accidents that were happening randomly¹⁵.

LOSOS: That's absolutely true. They evolved from three very different ancestors, and yet they ended up looking almost identical. They're all streamlined animals with a powerful tail for propulsion, two flippers for steering¹⁶ and a dorsal fin⁷ for stability. So the animals, if you saw one, you might - people mistake sharks for dolphins and the other way around. And so they have convergently evolved to be very similar. Now, the reason they've done that is that they have evolved a body form that is very optimally¹⁷ designed for moving quickly through water. And so in fact, if engineers were designing an animal to do that, that's pretty much the body shape they would pick.

SIEGEL: So the idea of convergent evolution is that common environmental factors would drive evolutionary change in some common directions. It's not all haphazard¹⁸ and accidental in that sense.

LOSOS: Yes, exactly. Convergent evolution most commonly occurs when species adapt to the same environmental circumstance in the same way.

SIEGEL: Has genomic research been the difference here? I mean, we've known for a long time that a shark and a dolphin are different. But is it that we can now see how unrelated an English finch¹⁹ and a very similar Australian finch are in a way that we couldn't see before?

LOSOS: That's exactly it. We've known about convergent evolution for a very long time. Charles Darwin remarked upon it in "On The Origin Of Species." But we had no idea how common it was. And that was until we've gotten a better idea of the evolutionary tree of life, of how species are related to each other. And the flood of molecular²⁰ DNA²¹ data that has come forth²² in the last two decades or so has in many cases revised our understanding about how species are related to each other. And it has revealed that many species that we thought were similar because they're closely related, that they're not closely related and that their similarity is the result of convergent evolution.

SIEGEL: Of course, one interesting speculative²³ debate is the question of whether life on other planets would resemble life on Earth. And accepting the power of convergence as a guiding principle, I guess the answer would probably be yes. There are structural²⁴ and environmental reasons for life developing as it has here. I mean, they would probably apply elsewhere.

LOSOS: We now know in just the last few years that there are many, many planets in the universe very similar to Earth - millions, maybe billions, in our own Milky²⁵ Way galaxy²⁶. And so many scientists think that if there are that many Earth-like planets - and what I mean by Earth-like is of similar size, chemical composition, running water, temperature and so on, so very similar in many respects to Earth. Many scientists believe if that's the case, that life perhaps inevitably²⁷ has evolved on some of them. And so the argument goes that if the environment is similar on those planets, then life would have evolved and adapted in the same ways. Some go so far to say even that beings very much like us, humanoidlike beings, would've evolved on those planets.

SIEGEL: You write about the three-spined stickleback fish. What wisdom do we gain from this species?

LOSOS: Well, the three-spined stickleback is another case of evolutionary convergence. In lakes in British Columbia, they have diverged²⁸ into two types - one that lives on the bottom of a lake foraging²⁹ in the mud in the bottom, the other in the open water catching³⁰ little invertebrates³¹. But what has happened is on six different lakes they have evolved into these two types that are indistinguishable from one lake to another. And in fact, on the University of British Columbia campus, they have developed an enormous complex of artificial ponds in which they have seeded them with sticklebacks to watch how they evolve over many generations.

SIEGEL: And when they sort out into open-water sticklebacks and bottom-feeding sticklebacks, at some point they become non-interbreeding different species of three-finned sticklebacks?

LOSOS: Well, the really interesting thing here is that, yes, in any one of those lakes, they adapt to the two different habitats. And eventually they become so that they don't interbreed with each other. However, if you put together the same type of fish from different lakes, even though they've independently adapted to those niches³², they will interbreed with each other.

SIEGEL: That's amazing. So in effect, biologists at the University of British Columbia are creating evolution.

LOSOS: Yes. Yes. That's exactly it. To my mind, this is the most exciting advance in evolutionary biology - perhaps one of the most exciting advances in all of science - in the last few years, the realization³³ that evolutionary change can occur not only very rapidly, but so rapidly that you can actually do experiments and expect to see an outcome in three to four years. This is something that Darwin got completely wrong.

I mean, Darwin was right about so many things. It is amazing. But he was completely wrong on the pace of evolution. He thought that evolution occurred so glacially slowly that it would take thousands of years to be able to detect it at all. Well, now that we know that evolution can occur very quickly, we can actually go out and do experiments in nature to test our ideas. And some of the experiments going on now are just extraordinary and providing incredible insight about the evolutionary process.

SIEGEL: Well, Jonathan Losos, thank you very much for talking with us about it and about your book.

LOSOS: Well, it's been my pleasure.

SIEGEL: Professor Losos' book is called "Improbable Destinies: Fate, Chance, And The Future Of Evolution."

1 contingencies   

n.偶然发生的事故，意外事故( contingency的名词复数 )；以备万一

参考例句：

• We must consider all possible contingencies. 我们必须考虑一切可能发生的事。
• We must be prepared for all contingencies. 我们要作好各种准备，以防意外。 来自辞典例句

2 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

3 radically   

ad.根本地，本质地

参考例句：

• I think we may have to rethink our policies fairly radically. 我认为我们可能要对我们的政策进行根本的反思。
• The health service must be radically reformed. 公共医疗卫生服务必须进行彻底改革。

4 insistence   

n.坚持；强调；坚决主张

参考例句：

• They were united in their insistence that she should go to college.他们一致坚持她应上大学。
• His insistence upon strict obedience is correct.他坚持绝对服从是对的。

5 contingency   

n.意外事件，可能性

参考例句：

• We should be prepared for any contingency.我们应该对任何应急情况有所准备。
• A fire in our warehouse was a contingency that we had not expected.库房的一场大火是我们始料未及的。

6 conversion   

n.转化，转换，转变

参考例句：

• He underwent quite a conversion.他彻底变了。
• Waste conversion is a part of the production process.废物处理是生产过程的一个组成部分。

7 fin   

n.鳍；(飞机的)安定翼

参考例句：

• They swim using a small fin on their back.它们用背上的小鳍游动。
• The aircraft has a long tail fin.那架飞机有一个长长的尾翼。

8 convergent   

adj.会聚的

参考例句：

• A curved-inwards wall has a convergent effect on wall spray.凹型壁面对碰壁喷雾有聚集作用。
• If a sequence is not convergent,it is divergent.如果一个序列不收敛，我们称它发散。

9 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

10 aquatic   

adj.水生的，水栖的

参考例句：

• Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
• We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。

11 dinosaur   

n.恐龙

参考例句：

• Are you trying to tell me that David was attacked by a dinosaur?你是想要告诉我大卫被一支恐龙所攻击？
• He stared at the faithful miniature of the dinosaur.他凝视著精确的恐龙缩小模型。

12 dorsal   

adj.背部的，背脊的

参考例句：

• His dorsal fin was down and his huge pectorals were spread wide.它的脊鳍朝下耷拉着，巨大的胸鳍大张着。
• The shark's dorsal fin was cut off by the fisherman.鲨鱼的背鳍被渔夫割了下来。

13 fins   

[医]散热片；鱼鳍；飞边；鸭掌

参考例句：

• The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关，与SBP、DBP无相关。 来自互联网
• Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句

14 sleek   

adj.光滑的，井然有序的；v.使光滑，梳拢

参考例句：

• Women preferred sleek,shiny hair with little decoration.女士们更喜欢略加修饰的光滑闪亮型秀发。
• The horse's coat was sleek and glossy.这匹马全身润泽有光。

15 randomly   

adv.随便地，未加计划地

参考例句：

• Within the hot gas chamber, molecules are moving randomly in all directions. 在灼热的气体燃烧室内，分子在各个方向上作无规运动。 来自辞典例句
• Transformed cells are loosely attached, rounded and randomly oriented. 转化细胞则不大贴壁、圆缩并呈杂乱分布。 来自辞典例句

16 steering   

n.操舵装置

参考例句：

• He beat his hands on the steering wheel in frustration. 他沮丧地用手打了几下方向盘。
• Steering according to the wind, he also framed his words more amicably. 他真会看风使舵，口吻也马上变得温和了。

17 optimally   

最佳

参考例句：

• In the classic script for a Cartel, the group sets a unified optimally exploiting price structure. 按照卡特尔的传统范本，这个集团制定出一个统一的最有利于剥削的价格结构。 来自辞典例句
• RF power LDMOS with a trench drift region is optimally designed. 对射频功率LDMOS槽形漂移区的结构进行了优化设计。 来自互联网

18 haphazard   

adj.无计划的，随意的，杂乱无章的

参考例句：

• The town grew in a haphazard way.这城镇无计划地随意发展。
• He regrerted his haphazard remarks.他悔不该随口说出那些评论话。

19 finch   

n.雀科鸣禽(如燕雀，金丝雀等)

参考例句：

• This behaviour is commonly observed among several species of finch.这种行为常常可以在几种雀科鸣禽中看到。
• In Australia,it is predominantly called the Gouldian Finch.在澳大利亚，它主要还是被称之为胡锦雀。

20 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

21 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

22 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。

23 speculative   

adj.思索性的，暝想性的，推理的

参考例句：

• Much of our information is speculative.我们的许多信息是带推测性的。
• The report is highly speculative and should be ignored.那个报道推测的成分很大，不应理会。

24 structural   

adj.构造的，组织的，建筑（用）的

参考例句：

• The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
• The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。

25 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

26 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。

27 inevitably   

adv.不可避免地；必然发生地

参考例句：

• In the way you go on,you are inevitably coming apart.照你们这样下去，毫无疑问是会散伙的。
• Technological changes will inevitably lead to unemployment.技术变革必然会导致失业。

28 diverged   

分开( diverge的过去式和过去分词 )； 偏离； 分歧； 分道扬镳

参考例句：

• Who knows when we'll meet again? 不知几时咱们能再见面！
• At what time do you get up? 你几时起床？

29 foraging   

v.搜寻（食物），尤指动物觅（食）( forage的现在分词 )；（尤指用手）搜寻（东西）

参考例句：

• They eke out a precarious existence foraging in rubbish dumps. 他们靠在垃圾场捡垃圾维持着朝不保夕的生活。 来自《简明英汉词典》
• The campers went foraging for wood to make a fire. 露营者去搜寻柴木点火。 来自辞典例句

30 catching   

adj.易传染的，有魅力的，迷人的，接住

参考例句：

• There are those who think eczema is catching.有人就是认为湿疹会传染。
• Enthusiasm is very catching.热情非常富有感染力。

31 invertebrates   

n.无脊椎动物( invertebrate的名词复数 )

参考例句：

• Insects and worms are all invertebrates. 昆虫和蠕虫都是无脊椎动物。 来自辞典例句
• In the earthworm and many other invertebrates, these excretory structures are called nephridia. 在蚯蚓和许多其它无脊椎动物中，这些排泄结构称为肾管。 来自辞典例句

32 niches   

壁龛( niche的名词复数 )； 合适的位置[工作等]； （产品的）商机； 生态位（一个生物所占据的生境的最小单位）

参考例句：

• Some larvae extend the galleries to form niches. 许多幼虫将坑道延伸扩大成壁龛。
• In his view differences in adaptation are insufficient to create niches commensurate in number and kind. 按照他的观点，适应的差异不足以在数量上和种类上形成同量的小生境。

33 realization   

n.实现；认识到，深刻了解

参考例句：

• We shall gladly lend every effort in our power toward its realization.我们将乐意为它的实现而竭尽全力。
• He came to the realization that he would never make a good teacher.他逐渐认识到自己永远不会成为好老师。